Apparatus for producing tubular articles having varying wall thickness



A ril" 29,1941.

F. M. DARNER 2,240,456 APPARATUS FOR PRODUCING TUBULAR ARTICLES HAVING VARYING WALL THICKNESS Filed Oct. 6, 1939 2 Sheets-Sheet 1 "INVENTOR. fEffifiE/C MpAr/vm ATTORNEYS April-29,1941. F. M. DARNER 2,240,456 ABPARATUS FOR PRODUCING TUBULAR'ARTICLES HAVING VARYING WALL THICKNESS Filed Oct. 6, 1939 2 Sheets-Sheet 2 INVENTOR. F/PEDl-iE/C MJJA ENE/TE ATTORNEYS view taken on line -5 of Figure 1;

Patented Apr. 29, 1941 APPARATUS FOR PRODUCING TUBULAR ARTICLES HAVING THICKNESS VAR-YING WALL Frederic M. Darner, Shaker Heights, Ohio, assig'nor to Republic Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Application October 6, 1939, Serial No. 298,285

2 Claims.

This invention relates to the manufacture of tubing and more particularly to certain improvements in the art of processing tubular products whereby predetermined variations may be imparted to the wall thickness of a tube and the outer diameter of the tube can be brought to the desired dimension.

There is a. substantial demand for tubing having a straight cylindrical outer surface and having the wall tapered, thereby producing a tube having a thick wall at one end and a thinner wall at the other end. Likewise tubular products are frequently called for having a uniform outer diameter and a regularly varying wall including relativelythick and thin sections.

It is among the objects of my invention to provide improved apparatus for drawing a tube through a die over a mandrel whereby predetermined variations may be imparted to the wall thickness of the tube automatically and in repeating cycles throughout the length bf the tube; Other objects of my invention are: the provision of a machine which can readily be set up to form different inside wall tapers and thick and thin sections on a tubular article; the provision of means which may be readily adapted to a standard draw bench for varying the wall thickness of a tube in predetermined fashion as a tube drawn through the die; the provision of simple and rugged means for producing tubular articles having varying wall thicknesses; and the provision of apparatus of the type described which can quickly and easilybe changed over to produce different tubular products.

The above and other objects of niy inventionv will appear from the following description of the preferred form thereof, reference being had to the accompanying drawings in which--- t Figure 1 is a fragmentary planview of a draw bench equipped with myimproved apparatus;

Figure 2 is a side elevation, on a somewhat smaller scale, of the ure 1; v

Figure 3 is an enlarged illustrative cross-sectional view through the die of the draw bench draw bench shown in Fi shown inFigures land 2, showing the die and mandrel and 'a tube which is being processed thereby; v

Figure 4 is an view taken online 4-4 ofFigure.1;

Figure 5 is an enlarged verticalcross-sectional Figure 6 is a detached view of the cam illustrated inFigures 4 and 5and employed in producing the tube shown in Figure 3;

enlarged verticalcross-sectional Figure '7 illustrates a differently contoured cam adapted to produce a tube having variations of wall thickness difierent from those of the tube shown in Figure 3.

Referring particularly to Figures 1 and 2, the draw bench may be of any usual form and in the illustrated embodiment comprises a main base or frame structure I having a centrally located section 2 which carries the die head 3. The die 4 (Figure 3) is carried in the head 3 and may of course be changed to accommodate different sizes of tubing.

A buggy or carriage 5 is mounted on wheels 6 which are in turn supported by the track member l. The hook 8 is securedto the bug y 5 and is adapted to engage a chain (not shown) which extends lengthwise between the tracks I. This chain and buggy arrangement is of course well known in the art. The buggy 5 also includes the usual tube-gripping jaws (not shown) which are mounted in the end 9 of the buggy and are adapted to grip the end of the tube which is preliminarily pushed through the die 4. In operation the buggy is rolled up until the end 9 is adjacent the die block 3. A tube to be processed, having one end reduced in diameter, is pushed through the die and the reduced end gripped in the jaws on the buggy. The hook 8 then engages the drive chain of the draw bench and the tube is drawn through the die.

As seen in Figure 3, a mandrel M having a generally cylindrical portion In and a tapering portion II is secured to the end of the mandrel rod I2 which extends the length of the base I and is secured at its outer end to a sliding traveler T, as will be more fully described later. A chain or other suitable drive member 13. is secured at one end to a post I4 on the carriage 5, passes around supports the bottom reach of thechain l3 so.

that it will pass freely over the die head 3.

It will ,be evident that, as the bug slnoved. away fromthe ,die head 3 during the operation of drawing a tube through the die, the chain I3 will cause the sprocket wheel I6 to-turn. This rotation of the sprocket-wheel l6 and theshaft .I8 employedtodrive the camshaftl 9 through.

the connectinggears 20 and 2| (seel li resui and 5-) The shaft l8 .issupported in bearing 22 and 23 on the frame structure 24 of the mandrel operating mechanism. This frame structure 24 includes longitudinally extending channels 25 and 26 having track or guide portions 21 secured thereto. These guides support the sliding traveler or crosshead T which, as is best seen in Figure 4, comprises longitudinally extending side members 28 cdnnected by end pieces 29 and 30. The mandrel rod 12 extends through the end piece 23 and is provided with a washer 3| and lock nuts 32 whereby the length of the bar l2, and thus the position ofthe mandrel M, may be adjusted. Slots 33 are cut in each of the side members 28 of the traveler T to permit the camshaft l9 to extend therethrough. As the camshaft I9 is supported in fixed bearings 34 and 35, which are mounted on the channels 25 and 26 respectively, it will be seen that the slots 33 permit longitudinal sliding movement of the traveler T. A cam follower roll 36 is mounted on the shaft 31 which extends between the sides 28 of the traveler T. This follower 36 engages the cam 38 which is keyed to and rotates with the cam shaft l9 and, as will be-subsequently explained, the contour of the cam 38 determines the variations in wall thickness which are. imparted to the tube as it is drawn through the die 4.

In Figures 4, and 6 the cam 38 is illustrated and in Figure '7 I have illustrated a cam of adiflerent shape. It will be understood that this cam can be made of any shape which will give the desired contour to the inner wall of the tube being processed.

In the operation of the above described apparatus a tube, preferably of greater diameter and greater wall thickness than the finished product, is slipped over the mandrel rod, which has been completely retracted from its working position within the die, the tube end is pushed through the die, and the jaws on the buggy are caused to grip the tube end. Then, as the buggy 5 moves away from the die head 3 is pulled through the die I. The drag of thetube walls against the 'mandrelend causes-.itjto'be drawn into the die opening (see Figure 31) as far as will be permitted by the lock nuts 32 and the engagement of the cam follower roll 36 with the surface of the cam 38. As the movement of the buggy continues the shaft I8 is rotated by the sprocket I3 and chain I3 rotation is imparted to the cam 38 as explained abovel The cam 38 revolves and variations in its contour will either cause the roll 36 to be moved away from the die head, thus withdrawing the mandrel M somewhat out of the die 4 and establishing a greater distance between the working surface of the mandrel andftheworking surface of the die, or will permit the drag of the tube upon the mandrel M to draw the mandrel further into the die opening, thus reducing the space between the working surface of the mandrel and that of the die. In the first instance, it will be observed that a relative thick tube wall will be formed which may be up to the thickness of the original tube. In the second instance, when the mandrel M moves further into the die opening, the thickness of the tube wall will be reduced. During the change, or while the mandrel is being moved,

a tapering action will take place on the tube wall and this can be made relatively gradual or steep,

depending upon the cam contour. To make a gradual taper the change of the diameter of the cam will be very slight'for each degree of circumference of the cam, while to make a sudden.

change in wall thickness a. substantial diiference in diame r. will be established in a relatively small number of degrees of the cam circumference.

In Figure 3 the tube comprises relatively thick wall sections A which are of substantially the same length as the intermediate relatively thin wall sections B. These sections A and B are connected by tapering wall portions C and D, the section 0 tapering in the opposite direction from the section D. In Figure 3 the mandrel is in its innermost position and this same position is also shown in Figure 4, where it will be observed that the roll 36 is engaging the portion of the cam 38 having the smallest diameter. In dot-and-dash lines in Figure 3 the retracted position of the mandrel M is indicated which will form the thick wall sections A of the finished product. This occurs when the cam 38, which normally rotates in clockwise direction as seen in Figures 4 and 6, reaches the point a. As the diameter of the cam remains constant until the point I) is reached, the mandrel will not move during this portion of the rotation of the cam and the uniform thick" wall portion A will be produced. From I) to'approximately the point e on the cam, the diameter is lessened. This will permit the roll 38, the traveler T, the mandrel rod l2, and the mandrel M to be drawn into the full line position of Figure 3, and during this movement of the mandrel into the die the tapered portion d will be formed. From 0 to d the cam diameter remains constant at its minimum value and this results in the formation of the straight, thin wall section B of the tube. From (Z to d the diameter of the cam 38 increases and this will form the tapered portion 0 of the finished tube. The length of ,the sections of the finished product depends upon the speed of rotation of the cam 38 and this in turn depends upon the gear ratio between the sprocket l6 and the cam 33. This may be changed by varying the relative sizes of the gears 28 and 2| and by varying the diameter of the sprocket l6.

After the draw bench has pulled the tube through the die, the tube is removed, the mandrel pulled back out of the die and the cycle repeated. The operating connections between the carriage 5 and the mechanism for moving the mandrel M into and out of the die, is such that the speed of drawing, i. e., the rate of travel of the buggy 5, will not in any way change the resulting product. Long or short lengths of tube can be processed up to the capacity of the draw bench and each section will be formed into a repeating string or series of identical sections.

The processed tubes may of course be cut up into lengths as desired and it will be observed that by varying the contour of the main cam 38 an infinite number of variations in the inner wall of the tube can be obtained. At the same time the outer diameter of the tube can" be brought to an exact and accurate value.

Although I have described the illustrated embodiment of my invention in considerable detail, it will be understood by those skilled in the art that numerous variations and modifications may be\made in the specific apparatus employed without departing from the spirit of my invention. I do not, therefore, wish to be limited to the particular form of my tube processing apparatus herein shown and described but claim as my invention all embodiments thereof in the scope of the appended cl I claim: 1

1. In a draw bench for producing tubular articles having varying wall thickness, a stacoming withtionary die, a movable carriage on one side oi said die for drawing .a tube through said die, means for. moving said carriage away from said die, a

- mandrel, a mandrel carrying rod extending away from said die on the opposite side thereof from said carriage, a travelermember supported for movement toward and away from said die, sliding connections between said traveler and said mandrel rod, a support for said traveler, cam

means carried by said support and operable to move said traveler, and driving means between said cam and said carriage whereby said cam will be moved in timed relation to the movement of said carriage in tube drawing direction, said driving means including a chain or the like secured to said carriage, supporting and guiding members for said chain; a sprocket for said chain on said support for said traveler and drivimi connections between said sprocket and said cam.

2. In a draw bench for producing tubular articles having varyingwall thicknesses the combination of a frame, a fixed die on said frame, a tube pulling carriage movable on the frame on one side of said die, means to actuate said carriage to pull a tube through said die, a traveller slidable in said frame on the other side oi said die, an axially movable mandrel adjacent to said die and connected to said traveller, a cam iollower on said traveller, a cam rotatably mounted in the irame and engaging said follower, and

means for actuating said traveller including a looped member connected to said carriage and a gear which is rotated by endwise movement oi said loop member and which serves to rotate said cam.

FREDERIC M. DARNER. 

